New Turret added: Phase Disruptor

- A new turret added to the game, called Phase Disruptor! This turret will mainly damage enemy shield, but it can also do reduced damage to enemy armor. It cannot, however, damage enemy health.

- Laser Turret's main damage changed to enemy armor and it also does reduced damage to enemy health, but it can no longer damage shield.

- Turrets now only target enemies they can actually damage. Gatling Guns and Laser Turrets do not target enemies with shield, Phase Disruptors do not target enemies without shield or armor, etc.